B&S model 31H7770202E1 18 HP (craftsman LT1000)

[PamG]

This engine is on a craftsman riding mower and will only run for 20 minutes from cold, and then 15 minutes after a 20 minute cooldown. Heat seems to be the issue. Have checked oil, airfilter, cap, plug and changed away from ethanol gas. It literally just dies…no rough running at any time. Someone on another forum suggested it could be the ignition going to open circuit when getting hot. Any suggestions?

 

[ILENGINE]

Ignition would be my first guess, but will need to confirm loss of spark after engine dies with a open gap spark tester, not a blink style tester. Need possible could be a failing fuel solenoid on bottom of carb, but that is not as common but does happen.

 

[PamG]

Ignition would be my first guess, but will need to confirm loss of spark after engine dies with an open gap spark tester, not a blink style tester. Need possible could be a failing fuel solenoid on bottom of carb, but that is not as common but does happen.

My seat has a sensor on it so the engine dies if I stand up…and that’s exactly how this engine is acting…like I got out of the seat at the 20 minute mark.

 

[PamG]

My seat has a sensor on it so the engine dies if I stand up…and that’s exactly how this engine is acting…like I got out of the seat at the 20 minute mark.

Ignition would be my first guess, but will need to confirm loss of spark after engine dies with a open gap spark tester, not a blink style tester. Need possible could be a failing fuel solenoid on bottom of carb, but that is not as common but does happen.

If the spark tester shows loss of spark at the 20 minute mark…what does that mean?

 

[ILENGINE]

If the spark tester shows loss of spark at the 20 minute mark…what does that mean?

That basically confirms that the ignition module is heat failing. And would require the replacement of the ignition module

 

[PamG]

Ok thanks.

 

[sgkent]

or ignition switch. get the VOM out and look for where the voltage disappears

 

[PamG]

You mean a multimeter? Not sure what a VOM is…..

 

[ILENGINE]

You mean a multimeter? Not sure what a VOM is…..

VOM=Volt Ohm Meter aka multimeter

 

[slomo]

My first thought is trash in the fuel tank. Might flush it out like new. Blow out with compressed air confirming she is spotless. As Bertsmobile1 said, there is clean and there is CLEAN.

New fuel lines might be called for. They deteriorate internally and can block flow. Probably a new fuel filter while you are there. Freshen up the ol' girl.